Week 1: How do we measure psychopathology Flashcards
What do developmental psychopathologists measure
Psychopathology/symptoms Predictors, correlates and consequences of psychopathology Behavioral Neural Physiological Neural Cognitive
Reliability
3 Things
How consistent it the measure?
Internal consistency:
Are reports on items measuring the construct consistent? If a measure is reliable, scores from people with the construct should be highly correlated with each other.
Test-retest reliability: Do we get the same answer on different occasions? Sometimes we would not expect to (mood) but if we think the construct is stable, we expect this.
Inter-rater reliability: Agreement between 2 people judging whether something is present or absent.
2 people using the same system should reach the same conclusion.
Validity
2 things
Does the measurement assess what we want it to?
Convergent validity:
Are scores on the measure related to other measures or indicators of the same construct?
Discriminant validity:
Are the scores on the measure different from scores of measures designed to measure other constructs? If not, are the measuring the thing you designed thm to measure?
Categorical vs Dimensional
Cat = difference in kind
Dim = difference in degree`
Unstructured interviews
Clinician asks questions and arrives at diagnosis
Super common
Unstructured interviews - problems
Challenges:
Less comprehensive - clinicians make diagnoses before they have heard all the info. May miss things.
Biases may affect diagnosis
Confirmation bias:
Tend to selectively collect information that confirms diagnosis they believe the patient has
Ignore disconfirmatory information
Use an availability heuristic:
Make decisions based on things that came up recently
eg if you diagnose ADHD this morning, might be more likely to do it again this PM.
Semi-structured and structured interviews
Has a set of questions that are presented to the respondent
Improves comprehensiveness
Reduces bias
Semi-structured means the interviewer has a lot of leeway to ask follow up questions and means clinical judgement forms part of the diagnosis.
Structured - interview is strictly controlled
Can be done by a PC
Unstructured vs semi or structured
Semi/structured are more reliable and valid
Can be used categorically or dimensionally (by tallying the symptoms)
Disadvantages of semi or structured
Standard in research, rare in clinical work
Too long
Cant fit into the hours you have funding for
Need advanced training to do right
Rating scales
Often used to measure continuously
Can be used categorically too
Short, no interviewer
Historically thought to be worse than interviews. Evidence suggests may not be true.
Raises the possibility that this could lead to standardized diagnoses, would be good (takes less time)
Observations
May want to to observe behavior directly
Without training, hard to say if something is normative or not (eg tantrums in kids and moodiness in teens)
Observation provides access to the circumstances in which behavior occurs which can provide useful info
Naturalistic observation
Natural environment
Very rich can see antecedent-behavior-consequence
ie if a behavior always gets the child’s way, it is obvious why they keep doing it
Structured observation
Lab/clinic
Designed to see child’s response to a situation
You could give them an online game in which a “peer” provokes them but in reality its a confederate.
Observation - Challenges
Feasibility - labor intensive
External validity - presence of observer chances behavior (not in young kids)
May not see the same results as “real world”
May be hard to see the behavior of interest:
Low base-rate (rare)
Covert:
eg relational aggression
Creative solutions have worked for this eg
wireless microphones
Provocation in labs
Who do we get info from to assess?
Parents, children and teachers usually
Disagreement among informants
Often do not agree - r from .2 to .4
Used to think this was error
BUT different informants provide reliable and valid responses
eg teacher report is reliable and correlates with other measures
Both show “good info”
Why do informants disagree?
Different perspectives
(1) Different perspectives
Rater-specific factors (biases):
Maternal depression associated with overreporting behavioral problems
May see differences between school and mother if mother is overreporting
Legitimate differences in the meaning of behaviors across settings:
Parents/teachers interact with kids in different contexts and these may change the interpretation of behavior
Teachers may see assertive behavior as oppositional, parents might not
These differences may tell us important things about a child’s adaptation in different environments; they could ne struggling at school and not at home.
Why do informants disagree?
Situation specificity
Children behave differently across different situations
These have different demands (school requires socializing, might be harder for a shy kid than home)
Inter-rater differences may capture real differences in behaviour in different settings
Parents and teachers may see different things
Using data from multiple informants
and or
combine or keep seperate
You can combine date from different sources via the “and” rule or the “or” rule
“Or” rule:
Symptom is present if any informant says it is
“and” rule
Symptom is only present if all informants agree
Or symptom is most common
Neither captures the idea that differences between the two raters are valuable
Diagnosis as reported by a teacher may be different from that reported by a parent
Might be useful to keep parent’s, teacher’s and combined reports separate
And or symptom rule
Symptom based are when you co bine symptoms ie
And = both parent and teacher say a symptom is present
Or = either parent or teacher say symptom is present
Or symptom is the most common
And or diagnosis rule
Here the condition is diagnosed if
AND RULE
By adding up symptoms from the parents report you reach threshold for a diagnosis
AND
By adding up symptoms from the teacher’s report, you reach threshold
BOTH REPORTS MUST BE ABOVE THRESHOLD TO DIAGNOSE
OR RULE
By adding up symptoms from the parents report you reach threshold for a diagnosis
OR
By adding up symptoms from the teacher’s report, you reach threshold
ONLY ONE REPORT NEEDS TO BE ABOVE THRESHOLD TO DIAGNOSE
